Update postgres client libraries to 16.4

In preparation for Postgres 16 testing, we need to update the the client pg libs in this project. This allows for support of backup/restore to PG16, while still retaining support for previous postgres versions. (This has no impact on the version of postgres running as part of the chart, just which version the client libs are built with).

See !1212 (merged) for example of last time this was done with PG 15.1.

Update 2024-0-9-05: Current version now available in Omnibus is 16.4